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Hollinger Corp. 
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DEPARTMENT OF COMMERCE 



Technologic Papers 

OF THE 

Bureau of Standards 

S. W. STRATTON, Director 



No. 13 2 

mechanical properties and resistance to 

corrosion of rolled light alloys of 

aluminum and magnesium with 

copper, with nickel, and 

with manganese 

BY 

* 

P. D. MERICA, Physicist 

R. G. WALTENBERG, Assistant Physicist 
i 

and 

A. N. FINN, Associate Chemist 

i 
Bureau of Standards 



ISSUED OCTOBER 25, 1919 



to °i 




PRICE, 5 CENTS 

Sold only by the Superintendent of Documents, Government Printing Office, 
Washington, D. C. 

WASHINGTON 

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1919 









Ms* 






n s of -. 

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-* 






MECHANICAL PROPERTIES AND RESISTANCE TO CORROSION 
OF ROLLED LIGHT ALLOYS OF ALLUMINUM AND MAGNE- 
SIUM WITH COPPER. WITH NICKEL, AND WITH MANGANESE 



By P. D. Merica, R. G. Waltenberg, and A. N. Finn 



CONTENTS 

Page. 

I. Introduction 3 

II. Preparation of the alloys 4 

III. Composition of the alloys 5 

IV. Mechanical tests 5 

V. Corrosion tests 9 

VI. Summary 12 

I. INTRODUCTION 

Certain compositions of the light, i. e., aluminum-rich, alloys 
of aluminum with magnesium and copper have become quite 
well known within the past 10 years under the name of duralumin. 
These alloys are used for rolling and forging and can be so treated 
as to develop quite remarkable mechanical properties. Thus a 
properly heat treated alloy containing about 4 per cent of copper 
and about 0.5 per cent of magnesium, rolled into sheet or rod, 
will have a tensile strength of approximately 55 000 pounds per 
square inch, with an elongation in 2 inches of about 1 5 per cent. 
This alloy, duralumin, was developed by Wilm, 1 and its properties 
more fully described by Cohn. 2 

The authors considered it worth while to investigate the me- 
chanical possibilities of the light alloys of two somewhat analo- 
gous ternary series; namely, of aluminum-magnesium- nickel and 
of aluminum-magnesium-manganese, to study the effect of vari- 
ation of composition upon mechanical properties within the alumi- 
num-rich group of the aluminum-magnesium-copper alloys and to 
compare the mechanical properties of the three ternary series. 

1 A. Wilm, Physical-metallurgical investigations of aluminum alloys containing magnesium, Metallurgie, 
8, pp. 225, 650; 1911. 

* I,. M. Colm, Duralumin, Zcit. z. Bcfiirderung tl. Gewerbefleisses. 8!>, p. 043; 1910. Also in Electro 
te'ehnik u. Maicbmenbaui ; ">, pp. 809, 829; 1912. 

121484°— 19 3 



4 



Technologic Papers of the Bureau of Standards 



This work was carried out with the cooperation of the Alumi- 
num Co. of America; the alloys were prepared there and most of 
the mechanical tests were performed by Mr. Waltenberg in the 
laboratories of the company at New Kensington. The authors 
wish to express their appreciation of the aid and assistance thus 
given by the company through E. Blough. 

No previous investigation has been made, or at least published, 
of these three ternary systems, except that dealing with the com- 
positions called duralumin mentioned above. Light alloys of 
other related alloy series have been prepared and their properties 
investigated, viz, those of aluminum-copper, 3 of aluminum- 
manganese, 4 of aluminum-nickel 4> 5 , of aluminum-magnesium, 4 
of aluminum-manganese-copper, and of aluminum-nickel-copper. 3 

II. PREPARATION OF THE ALLOYS 

The alloys were prepared by melting standard 99 per cent 
aluminum ingots with the proper amount of aluminum hardener, 
consisting of an alloy of aluminum and the magnesium, copper, 
nickel or manganese depending upon the alloy to be produced. 
The melts were made in crucibles, attention being given to see 
that the temperature during melting did not exceed 8oo° C, as 
above this temperature the ingots poured from crucibles are apt 
to be porous and unsound due to the absorption of gas by the 
metal. The melting temperature was usually about 700 C. 
The molten metal was poured into water-cooled iron molds giving 
ingots 3.5 by 12 by 24 inches in dimensions. 

These ingots were reheated to from 400 to 450 C in a large 
reheating furnace, sent to the hot rolls, rolled and cross-rolled at 
these temperatures to a thickness of 0.25 inch. They were 
then allowed to cool in the air and cold rolled to 0.081 inch thick- 
ness (No. 12 B. & S.), annealed at from 400 to 450 C, rolled cold 
to 0.051 inch thickness (No. 16 B. & S.), annealed again and 
finished cold at 0.032 inch thickness (No. 20 B. & S.). 

Test specimens prepared from these sheets were tested (1) in 
the cold rolled condition, (2) after annealing at 422 C, and (3) 
after heat treatment, consisting of quenching at various tempera- 
tures and allowing the quenched specimens to stand or "age" 

3 H. C. H. Carpenter and C. A. Edwards, Alloys of aluminum and copper, Proc. Inst. Mech. Engineers, 
p. 57; 1907. 

1 H. Schirmeister, Investigations of binary aluminum alloys, Stahl u. Eisen, 35, pp. 64S, 873; 191s- 

6 A. A. Read and R. H. Greaves, The properties of some aluminum-nickel and of aluminum-nickel- 
copper alloys, Joum. Inst. Met., 13, p. 100; 1915. 

6 W. Rosenhain and F. C Lantsberry, Alloys of copper, aluminum and manganese, Proc. Inst. Mech. 
Engineers, p. 119; 1910. 






Properties of Light Alloys 5 

for several days before testing. The latter feature of this heat 
treatment will henceforth be termed "aging," and is necessary 
in order to develop the highest mechanical properties in the light 
alloys of the aluminum-copper- magnesium series. It will be 
noticed that some of the alloys of the latter series were aged at 
no° C, whereas those of the others were aged only at about 
room temperature (20 C). 

III. COMPOSITION OF THE ALLOYS 

It was desired to include in the list of alloys which were to be 
prepared compositions of each ternary series with the individual 
percentages of the components varying by intervals of 1 per cent 
and with a total combined content of hardening components not. 
exceeding 4.5 per cent, since with a smaller aluminum content 
these alloys can not be readily rolled into sheet. The actual 
compositions obtained as determined by chemical analysis are 
given in Table 1 . The B series is that containing manganese, 
the C series that containing copper, and the D series that con- 
taining nickel. 

IV. MECHANICAL TESTS 

The results of the tests made on the strips cut from the sheets 
are given in the Tables 2,3, and 4. 

TABLE 1.— Chemical Composition of Alloys « 



Number 



Al 


Mg 


Cu 


Per cent 


Per cent 


Per cent 


97.00 


1.15 


0.02 


97.17 


None 


.04 


96.14 


1.09 


.15 


98.02 


None 


.08 


95.08 


2.03 


.08 


96.86 


1.44 


.10 


96.31 


1.99 


.03 


97.27 


1.16 


.72 


96.69 


2.37 


.04 


97.15 


None 


2.15 


96.65 


2.84 


.04 


96.11 


None 


3.19 


96.72 


2.03 


.72 


96.62 


1.00 


1.80 


96.68 


1.07 


1.67 


95.98 


3.50 


.08 


95.83 


2.95 


.74 


95.51 


1.26 


2.58 


95.74 


.46 


3.18 


95.48 


.64 


3.22 



Mn 



Ni 


Fe 


Per cent 


Per cent 


None 


0.48 


None 


.76 


None 


.56 


None 


.44 


None 


.76 


None 


.40 


None 


.41 


None 


.56 


None 


.62 


None 


.36 


None 


.27 


None 


.40 


None 


.30 


None 


.35 


None 


.33 


None 


.26 


None 


.27 


None 


.41 


None 


.34 


None 


.39 



Si 



B-l... 
B-2... 
B-3... 
B-4... 
B-5... 
B-6... 
B-7... 
C-l... 
C-2... 
C-3... 
C-4... 
C-5... 
C-6... 
C-7... 
C-8... 
C-9. . . 
C-10.. 
C-ll.. 
C-12.. 
A-l-12 



Per cent 

1.04 

1.71 

1.68 

1.07 

1.68 

.93 

.94 

None 

None 

None 

None 

None 

None 

None 

.02 

None 

None 

.02 

None 

None 



Per 



cent 
0.31 
.32 
.38 
.39 
.37 
.27 
.32 
.29 
.28 
.34 
.20 
.30 
.23 
.23 
.23 
.18 
.21 
.22 
.24 
.27 



"Aluminum determined by difference 



Technologic Papers of the Bureau of Standards 

TABLE 1— Continued. 



Number 


AI 


Mg 


Cu 


Mil 


Ni 


Fe 


Si 


E-3 


Per cent 
96.80 
97.44 
97.47 
95.82 
96.04 
96.70 
95.62 
95.14 
94.65 
95.41 


Per cent 

1.06 

.98 

None 

None 

1.18 

1.84 

1.94 

None 

.94 

2.86 


Per cent 

1.56 
.02 
.08 
.02 
.08 
.06 
.04 
.06 
.09 
.06 


Per cent 
None 
None 
None 
None 
None 
None 
None 
None 
None 
None 


Per cent 
None 

1.00 
1.76 
3.40 
1.98 
.80 
1.80 
3.94 
3.54 
1.08 


Per cent 

.32 
.36 
.44 
.44 
.48 
.43 
.46 
.58 
.65 
.39 


Per cent 

.26 


D-l 


.20 


D-2 


.25 


D-3 


.32 


D-4 


.24 


D-5 


.17 


D-6 


. 14 


D-7 


.28 


D-8 


.13 


D-9 


.20 







TABLE 2. — Mechanical Properties of Alloys of Aluminum-Magnesium-Manganese 







As rolled 


Annealed at 371° C 


Annealed at 422° C 


Quenched from 500° C, 
aged 8 days at 20° C 


Num- 
ber 


Sclero- 
scope 
hard- 
ness a 


Ultimate 
tensile 
strength 


Elonga- 
tion 
in 2 

inches 


Sclero- 
scope 
hard- 
ness a 


TJltimate 
tensile 
strength 


Elon- 
gation 
in 2 
inches 


Sclero- 
scope 
hard- 
ness a 


TJltimate 
tensile 
strength 


Elonga- 
tion 
in 2 

inches 


Sclero- 
scope 
hard- 
ness a 


Ultimate 
tensile 
strength 


Elon- 
gation 

in 2 
inches 


B-l 


30.0 


Lbs./in.2 
32 400 


P. ct. 

2.0 


13.5 


Lbs./in.2 

25 500 


P. ct. 

14.0 


11.5 


Lbs./in.s 
24 700 


P. ct. 


12.0 


Lbs./in.* 

22 300 


P. ct. 

22.0 






31 600 


2.0 




25 300 






24 700 


13.0 




23 100 


25.0 






32 400 


2.5 




25 900 


19.0 




23 400 


11.5 




22 900 


17.0 






31 000 


2.0 




















B-2 


20.0 


24 000 


4.5 


10.5 


16 800 


26.0 


8.5 


16 000 


30.5 


8.5 


14 200 


36.5 






22 000 


3.5 




16 700 


24.0 




16 000 


35.5 




14 600 


36.5 






24 100 


4.0 




16 200 


31.0 




15 800 


30.0 




14 400 


35.0 


B-3 


32.0 


34 600 

35 000 


2.0 
2.0 








14.0 


26 400 
26 000 


14.0 


14.0 


25 300 
24 700 


18.0 










17.5 






35 600 


2.5 










25 800 


12.0 




24 900 


20.0 


B-4 


20.0 


21 500 

22 500 










6.5 


14 300 
13 700 


42.0 
41.0 


7.0 


12 800 
12 900 


26.0 




3.0 








40.0 






22 100 


3.0 








# 


13 300 


41.0 




12 300 


35.0 






23 500 


3.0 
























22 900 


3.0 
























22 300 


5.5 
























23 500 


4.0 




















B-5 


36.0 


39 300 

40 300 


2.0 
2.0 








13.5 


29 400 
28 600 


20.0 
16.0 


15.0 


28 800 

29 400 


16.0 










15.0 






37 500 


2.0 










28 600 






28 000 




B-6 


36. 5 


45 000 
42 700 


3.5 
2.5 








14.0 


33 100 


13.0 


15.5 


34 100 
33 100 


19.0 










17.0 
























32 600 


17.0 


B-7 


35.5 


37 200 
40 700 


2.5 
4.0 








13.0 


29 600 
29 200 


15.5 
17.0 


14.0 


29 000 
29 000 


19.5 










19.5 
























29 400 


18.0 



o Taken with magnifying hammer. 



- 



Properties of Light Alloys 7 

TABLE 3. — Mechanical Properties of Alloys of Aluminum-Magnesium-Copper 





As rolled 


Annealed at 422° C 


Quenched from 510° C 
a,20°C; b, 110 


. Aged: 
C 


Num- 
ber 


Sclero- 
scope 
hard- 
ness a 


Ultimate 
tensile 
strength 


Elonga- 
tion in 
2 inches 


Sclero- 
scope 
hard- 
nessa 


Ultimate 
tensile 
strength 


Elonga- 
tion in 
2 inches 


Sclero- 
scope 
hard- 
ness o 


Ultimate 
tensile 
strength 


Elonga- 
tion in 
2 inches 






Lbs./in. 2 


Per cent 




Lbs./in. 2 


Per cent 




Lbs./ln.* 


Per cent 


C- 1 


42 


49 000 
48 400 


2.0 
2.5 


15.5 


33 300 
33 100 




17 


(38 030 
a- 
}37 220 


17.0 




15.0 


16.5 






48 600 


2.5 




32 700 


14.0 


27 


. f48 120 
147 210 


16.0 






49 600 


2.5 










18.5 


C- 2 


19 


25 800 


4.0 


7.5 


16 600 


35.0 


8 


(16 670 


34.0 






23 600 


3.0 




15 900 


35.0 




a jl6 670 


33.0 






23 600 


3.5 




16 100 


33.0 


8 


(16 510 
[16 510 


28.0 


















33.0 


C- 3 


35 


34 900 


2.5 


7.0 


21 600 


31.0 


13 


(26 350 


19.0 






35 700 
34 000 






21 800 

22 000 


33.0 
33.5 


11 


3 l27 690 
(29 420 
127 790 


11.5 




1.5 


20.0 


















19.5 


C- 4 


37 


38 400 
38 600 




10.5 


29 200 
29 200 


18.0 
18.0 


11 


(30 060 
129 700 


23.0 




1.5 


16.5 






37 200 


1.5 




29 400 


21.0 


14 


bP 59 ° 
[31 350 


19.0 


















20.0 


C- 5 


34 


35 900 
37 500 




8.0 


23 000 
22 400 


30.0 
28.5 


14 


(31 960 
a {30 500 


15.5 




2.5 


14.0 






37 700 


2.0 




22 800 


32.5 


14 


(30 910 


19.0 




38 


35 300 
38 500 


1.0 
0.5 


13.0 


30 500 
29 900 




15 


[33 970 

(33 370 

a J33 950 




C- 6 


17.0 




18.5 


23.5 






38 100 


1.5 




30 800 


16.0 


26 


143 190 
143 560 


18.5 


















18.0 


C- 7 


44 


44 200 


2.0 


17.0 


35 300 


26.0 


24 


(45 650 
a l45 740 


18.5 






45 500 


2.0 




'34 600 


25.5 




19.5 




38 


45 300 
38 100 




12.5 


34 800 
28 500 


25.0 
. 18.5 


35 


b 53 970 
{52 250 


20.0 




1.5 




C- 8 






38 


38 100 

41 200 




12.0 


29 100 
31 600 


18.5 
17.5 


13 


[29 120 




C- 9 


1.5 


21.0 






43 200 


1.5 




31 200 


17.5 




a J29 500 


22.0 






41 200 


1.5 




30 500 




14 


[30 270 
{30 270 


23.0 






22.0 


C-10 


45 


44 800 


1.5 


12.0 


30 600 


19.0 


14 


(37 430 
a {37 630 


24.5 






44 600 


1.5 




30 200 


19.0 




21.5 






47 500 


1.5 




30 200 


17.0 


26 


(47 690 
[47 690 


21.5 


















22.5 


C-ll 


50 


56 700 


2.0 


15.5 


34 900 


20.5 


29.5 


(51 520 
(50 870 


21.0 






52 900 


1.5 




36 000 


24.0 




24.0 






58 400 


2.0 








34 


. [54 740 
(55 590 


23.0 


















20.0 


C-12 


31 


38 900 


5.0 


7.5 


23 100 


24.0 


25-28 


[42 370 


14.5 






38 600 


5.0 




23 000 


24.0 


26 


[39 340 
[49 230 
149 830 


16.5 
26.5 


















25.5 



a Taken with maRnifyinR hammer. 



8 Technologic Papers of the Bureau of Standards 

TABLE 4. — Mechanical Properties of Alloys of Alnminnm-Magnesium-Nickel 





As rolled 


Annealed at 500" C 


Quenched from 500° C. 
Aged 20 days, at 20° C 


num- 
ber 


Sclero- 
scope 
hard- 
ness a 


Ultimate 
tensile 
strength 


Yield 
point 


Elonga- 
tion in 
2 inches 


Sclero- 
scope 
hard- 
ness a 


Ultimate 
tensile 
strength 


Elonga- 
tion in 
2 inches 


Sclero- 
scope 
hard- 
ness a 


Ultimate 
tensile 
strength 


Elonga- 
tion in 
2 inches 


D-l 


23 


Lbs./in. 2 
23 800 




Per cent 
3.0 


7 


Lbs./in. 2 
17 800 


Per cent 

15.0 


15 


Lbs./in. ° 
27 700 


Per cent 
18.0 






25 500 


21 000 


3.5 


7 


17 900 


18.5 


14 


26 200 


21.0 


D-2 


22 


24 900 


17 500 


2.5 


7 


18 000 


29.5 


7.5 


18 600 


28.5 






25 200 


IS 000 


2.5 


6.5 


17 700 


24.0 


7 


18 600 


27.0 


D-3 


27 


32 100 




3.0 


8 


21 600 


27.0 


10 


21 600 


24.0 




27.5 


32 600 
29 900 




3.5 

2.0 


8 
9.5 


20 600 
20 900 


29.0 
20.0 


9 
13 


21 600 
27 900 


20.0 


D-4 


25 500 


18.0 






29 300 


25 500 


2.5 


9.5 


21 100 


20.5 


14 


27 100 


17.0 


D-5 


29 


33 000 


30 000 


4.0 


10 


24 200 


21.0 


12 


28 100 


19.0 






34 300 


29 000 


4.5 


11 


21 100 


16.5 


12.5 


27 600 


18.5 


D-6 


30 


' 36 900 


31 000 


1.5 


11 


25 200 


18.0 


14 


29 900 


20.0 






35 200 


31 000 


1.0 


12 


25 400 


18.5 


13.5 


29 100 


21.5 


D-7 


24 


29 200 


21 000 


3.0 


10 


20 200 


23.0 


9 


22 700 


21.5 






29 300 


21 000 


3.0 


10 


20 200 


24.5 


10 


22 400 


21.0 


D-8 


28 


33 800 


28 500 


2.5 


10.5 


21 400 


19.0 


16 


31 000 


15.5 






34 100 


29 000 


1.5 


11 


22 600 


19.0 


15 


31 500 


15.0 


D-9 


32 


42 000 
40 600 


35 000 
34 500 


3.0 
3.0 


13 
13.5 


28 900 
28 800 




14 
15 


32 200 
31 800 


18.0 






16.0 









a Taken with magnifying hammer. 

From a study of these tables several facts are apparent. 

The alloys of aluminum-manganese and of aluminum-manganese- 
magnesium are not improved by heat-treatment of the type used 
for duralumin. The alloys of aluminum-nickel alone are also not 
appreciably affected b}^ this heat- treatment (see Nos. D-2, D-3, 
and D-7) , but in those alloys in which both nickel and magnesium 
are present the heat-treated specimens are harder and stronger 
than the annealed ones. 

Within the C series it is noticed that alloys containing magnesium 
but no copper are not improved by heat-treatment; alloys con- 
taining copper but no magnesium are moderately affected; the 
greatest increases in hardness and strength are found in the heat- 
treated specimens of alloys containing both copper and magnesium. 

Table 5 gives a survey of the percentage increase of strength 
of the heat-treated over the annealed specimens of the same 
composition. 

In the annealed condition and for equal additions, either with 
or without magnesium, copper seems to confer the greatest 
hardening effect, next manganese, and then nickel. This is 
shown in the comparisons of Table 6. 







Properties of Light Alloys g 

At about 3 per cent, magnesium alone appears to exert a greater 
hardening effect than the same percentage of the other metals, 
but at about 2 per cent exerts a lesser effect than that of copper. 

TABLE 5. — Percentage Increase of Tensile Strength of Heat-treated Specimens over 
Annealed Ones of the Same Composition 



Alloys containing — 


Average 
increase 


Alloys containing — 


Average 
increase 


Manganese, no magnesium B-2 (—9 per 
cent) B-4 (—7 per cent) 


Per cent 

-8 

-3 
6 

27 


Copper, no magnesium C-3 (28 per cent) 
C-5 (41 per cent) 


Per cent 
34 


Manganese and magnesium B-l (—4 per 
cent) B-3 (-5 per cent) B-5 (0) B-6 (0) 
B-7 (—2 per cent) 


Magnesium, no copper C-2 (3 per cent) 
C-4 (10 per cent) C-9 (—3 per cent) 

Copper and magnesium C-l (44 per cent) 
C-6 (43 per cent) C-7 (50 per cent) C-10 
(58 per cent) C-ll (57 per cent) C-12 


3 


Nickel, no magnesium D-2 (3 per cent) 
D-3 (3 per cent) D-7 (12 per cent)...... 

Nickel and magnesium D-l (40 per cent) 
D-4 (31 per cent) D-5 (24 per cent) D-6 
(17 per cent) D-8 (41 per cent) D-9 (11 


60 











TABLE 6. — Comparison of the Hardening or Strengthening Effect of Copper, of Nickel, 
of Manganese, and of Magnesium on the Annealed Specimens 



Number 



Composition 



Tensile 
strength 



Elongation 



C-3. 
B-2. 
D-2 

C-2. 
C-5. 
D-3 
C-4. 
C-l. 
B-l. 
D-l 
C-7. 
B-3. 
D-4 
C-6. 
B-5. 
D-6 



Cu 2.15 

Ma 1.71 

Ni 1.76 

Mg 2.37 

Cu 3.19 

Ni 3.40 

Mg 2.84 

Cu 1.16 Mg 0.72 

Mn 1.04 Mgl.15 

Ni 1.00 Mg 0.98 

Cu 1.80 Mg 1.00 

Mn 1.68 Mg 1.09 

Ni 1.98 Mg 1.18 

Cu 0.72 Mg 2.03 

Mn 1.68 Mg2.03 

Ni 1.94 Mg 1.94 



Lbs./in.2 
21800 
16000 
17800 
16000 
22800 
21100 
29000 
33000 
24000 
17700 
35000 
26000 
21000 
30000 
29000 
25000 



32 
32 
27 
35 
30 
28 
19 
15 
12 
17 
25 
13 
20 
17 
18 
18 



V. CORROSION TEST 

The resistance of these alloys to corrosion was determined by 
the salt spray test. This test consists of exposing the samples to 
a continuous fog of salt water, produced by atomizing a 20 per 
cent solution of salt (sodium chloride) in water. 7 

7 A. N. Finn. Method of Making .Salt Spray Test, Proc. Am. Soc. Test. Mats., XVIII, Part i. p. 937; 

ibi8. 



io Technologic Papers of the Bureau of Standards 

Although this test is not considered as entirely satisfactory, it 
is thought that the results produced represent with a fair degree 
of accuracy the results obtained in actual service, especially under 
marine conditions. 

The alloys were subjected to the salt spray test for two periods 
of one month each, and were examined at the, end of each period 
to determine the relative amount of corrosion. This was esti- 
mated by appearance only as it is practically impossible to deter- 
mine it by loss in weight on account of the adherence of the 
aluminum rust and the lack of a satisfactory reagent to remove 
the rust without affecting the metallic aluminum. 

The test pieces were 4 by 2 by 0.03 inches and included each 
series of alloys treated as follows: (1) as rolled (marked B-4, etc.), 
(2) quenched from 520 C into water at 16 C (marked B-4-A, 
etc.), (3) quenched from 520 C into water at ioo° C (marked 
C-2-B, etc.), (4) annealed at 450 C and cooled slowly (marked 
B-4-C, etc.). Specimens of commercial sheet aluminum, (1) as 
rolled marked (Al), (2) annealed at 450 C (Al-A), (3) annealed 
at 500 C (Al-B), and (4) quenched from 500 C (Al-C) were 
tested in the same way. 

After one month's exposure to the salt spray there was a marked 
difference in the appearance of the various rolled alloys. B-4 
and B— 5 as rolled, annealed, and quenched were only slightly 
corroded and appeared better than the remaining alloys. The 
annealed specimens, B-4— C, and B-5-C were corroded more than 
the rolled or the quenched specimens of these alloys. 

Specimens of D— 3, D-6, and D— 8, rolled, annealed, and quenched 
were not quite as good as the B series. The specimens as rolled 
were corroded a little more than the annealed or quenched 
specimens. 

The rolled specimens of the C series (C— 2, C-5, C— 8, etc.), with 
the exception of C-2 were badly corroded. C-2, as rolled, an- 
nealed, and quenched, C-11 annealed and quenched, and the 
quenched specimens of the remainder of this series compared 
favorably with B-4 and B-5. 

Figs. 1,2, and 3 show the appearance of some of the specimens 
after one month's exposure. 

In the following table the alloys are grouped according to their 
resistance to corrosion, as indicated by their appearance at the 
end of the second month, group I being the most resistant and 
group IV the least resistant. 







r 

.• 

«t 
to 

o 

lo- 
rn 




*£ ' ' 1 

• i 



•a. 



^ 



■ft. 



^ 



"==! 
■^ 



"ft. 



"fr 



■ft, 
■ft, 
O 



a, 



Properties of Light Alloys n 

Arrangement of Specimens in the Order of Their Resistance to Corrosion 



I 


II 


in 


IV 


B-5-A 


C-ll-B 


B-5-C 


C-ll-C 


C-ll 


B-4-A 


C-ll-A 


B-4-C 


C-2 


C-8 


B-5 


C-5-B 


B-4 


C-8-C 


C-5 


C-8-B 


C-5-A 


C-2-B 


D-3-A 


C-12 


C-8-A 


C-12-A 


D-6-C 


C-2-C 


C-5-C 




C-12-B 


D-6-A 


C-2-A 


C-12-C 






D-6 


D-3 


Al 






Al-A 


D-8 








Al-B 


D-3-C 








Al-C 


D-8-A 
D-8-C 





It must be stated that there was not the distinct difference 
in corrosive effect that might be inferred from the above classi- 
fication, but the difference was sometimes very small or negligible 
between pieces in the same group, and group I merges with group 
II, but the difference between groups II and III, and between 
III and IV is very definite. 

The order in which the 39 samples listed above are grouped 
is based on the opinion of two observers working independently 
of each other and it is noteworthy that the results of their observa- 
tions were in almost complete agreement. In no case was any 
sample placed by either observer in different groups than that 
indicated above, and in only a few cases did the indicated order 
differ. 

The following table gives, in condensed form, a summary of the 
corrosion tests and shows at a glance the relative resistance to 
corrosion of the alloys studied and the effect produced by quench- 
ing and annealing the rolled alloys. 

The figures in the table indicate the group in which a particular 
alloy was classed with respect to its resistance to corrosion. (See 
previous table.) 

Relative Corrosion 



Alloying metals 

As rolled 

Quenched 520° to 16° C. (A)., 
Quenched 520° to 100" C. (B) 
Annealed at 450° C. (C) 



B-4 



Mn 

3 

1 

(a) 

3 



B-5 



Mn- 
Mg 

1 
1 

(«) 
3 



C-2 



Mg 

3 
3 
3 
3 



C-5 



Cu 

4 
2 
2 



C-8, C-ll, 
C-12 



Cu-Mg 

4 
1 and 2 
1 and 2 
3 and 4 



D-3 



Nl 

3 
3 

(a) 
3 



D-6. 
D-8 



Ni-Mg 

3 
3 

(a) 
3 



Al 



4 
3 

(") 
3 



o No samples tested, 



12 Technologic Papers of the Bureau of Standards 

Consideration of this table indicates clearly that a decided 
difference in resistance to corrosion may be produced by quenching 
some aluminum alloys, a less marked difference is produced by an- 
nealing, and with some alloys no apparent difference is produced. 

The following conclusions are drawn from examination of this 
table: (i) If any change is produced by quenching, it improves the 
resistance of the metal to corrosion, (2) the magnesium, nickel, and 
nickel-magnesium alloys have about the same resistance to cor- 
rosion regardless of treatment, (3) annealing improves somewhat 
the resistance to corrosion of the copper-magnesium alloys and 
reduces the resistance of the manganese-magnesium alloy, (4) 
quenching produces the greatest effects in the copper, copper- 
magnesium, and manganese alloys, (5) commercial aluminum as 
hard rolled does not resist corrosion satisfactorily and the sample 
tested was almost completely disintegrated at the end of the test, 
showing characteristic exfoliation. Annealing or quenching ma- 
terially improves aluminum, but it is not equal to some of the 
alloys. 

VI. SUMMARY 

Ivight aluminum alloys of several compositions belonging to 
each of the three ternary series, aluminum-magnesium-copper, 
aluminum-magnesium-manganese, and aluminum-magnesium- 
nickel, were rolled out into sheet and tested in tension as cold- 
rolled, after annealing, and after heat treatment, consisting of 
quenching from about 500 C and aging at ordinary temperature. 

The alloys of the aluminum-magnesium-copper series were 
superior in all conditions to those of the other series in respect to 
tensile properties. 

The tensile properties of the aluminum-magnesium-copper 
series may be much improved by an appropriate heat treatment. 
The alloys of the aluminum-magnesium-nickel series are also 
improved by heat treatment, but not in the same degree as the 
former series. The alloys of the aluminum-magnesium-man- 
ganese series are not improved by heat treatment. 

Samples of representative compositions of each series were 
exposed to corrosion in the salt-spray test, and the appearance of 
the samples observed after one and after two months' exposure 
to the action of the salt spray. 

The alloys of the aluminum-magnesium-manganese series 
resisted corrosion in general better than those of the other series, 
and this agrees with other experience in the corrosion of such 



Properties of Light Alloys 



13 



alloys. The heat-treated specimens of the aluminum-magnesium- 
copper series were, however, but little inferior to those of the 
manganese series in their resistance to corrosion; the annealed 
and the cold-rolled samples of that series were the least resistant 
to corrosion of any of the alloys tested. Hard-rolled commercial 
aluminums corroded much more than any of the alloys. Annealed 
aluminum was more resistant to corrosion than the hard-rolled 
aluminum, but did not compare favorably with most of the 
alloys. 

Washington, February 27, 1919. 



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